
class Base64 {
    // private property 
    _keyStr
    mapEn
    mapDe
    _keyStr1
    mapEn1
    mapDe1
    _keyStr2
    mapEn2
    mapDe2
    constructor() {
        this._keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz+/=";
        this.mapEn = this._keyStr.split('');
        this.mapDe = {};
        for (let i = 0; i < this.mapEn.length; i++) {
            this.mapDe[this.mapEn[i]] = i;
        }
    }
    // public method for encoding 
    encode = (input, type?) => {
        let output = "";
        let chr1, chr2, chr3, enc1, enc2, enc3, enc4;
        let i = 0;
        input = this._utf8_encode(input);
        let mapEn = this.mapEn

        while (i < input.length) {
            chr1 = input.charCodeAt(i++);
            chr2 = input.charCodeAt(i++);
            chr3 = input.charCodeAt(i++);
            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;
            if (isNaN(chr2)) {
                enc3 = enc4 = 64;
            } else if (isNaN(chr3)) {
                enc4 = 64;
            }
            output = output + mapEn[enc1] + mapEn[enc2] + mapEn[enc3] + mapEn[enc4];
        }
        return output;
    }

    // public method for decoding 
    decode = (input, type?) => {
        let output = "";
        let chr1, chr2, chr3;
        let enc1, enc2, enc3, enc4;
        let i = 0;
        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
        let str = [...input]
        let mapDe = this.mapDe

        while (i < input.length) {
            enc1 = mapDe[str[i++]];
            enc2 = mapDe[str[i++]];
            enc3 = mapDe[str[i++]];
            enc4 = mapDe[str[i++]];
            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;
            output = output + String.fromCharCode(chr1);
            if (enc3 != 64) {
                output = output + String.fromCharCode(chr2);
            }
            if (enc4 != 64) {
                output = output + String.fromCharCode(chr3);
            }
        }
        output = this._utf8_decode(output);
        return output;
    }

    // private method for UTF-8 encoding 
    _utf8_encode = (string) => {
        string = string.replace(/\r\n/g, "\n");
        let utftext = "";
        for (let n = 0; n < string.length; n++) {
            let c = string.charCodeAt(n);
            if (c < 128) {
                utftext += String.fromCharCode(c);
            } else if ((c > 127) && (c < 2048)) {
                utftext += String.fromCharCode((c >> 6) | 192);
                utftext += String.fromCharCode((c & 63) | 128);
            } else {
                utftext += String.fromCharCode((c >> 12) | 224);
                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                utftext += String.fromCharCode((c & 63) | 128);
            }
        }
        return utftext;
    }

    // private method for UTF-8 decoding 
    _utf8_decode = (utftext) => {
        let string = "";
        let i = 0;
        let c = 0, c1 = 0, c2 = 0, c3;
        while (i < utftext.length) {
            c = utftext.charCodeAt(i);
            if (c < 128) {
                string += String.fromCharCode(c);
                i++;
            } else if ((c > 191) && (c < 224)) {
                c2 = utftext.charCodeAt(i + 1);
                string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                i += 2;
            } else {
                c2 = utftext.charCodeAt(i + 1);
                c3 = utftext.charCodeAt(i + 2);
                string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                i += 3;
            }
        }
        return string;
    }

}


export let base64 = new Base64();
